简介：Plantationresourceisanimportantcomponentofforestresources.OverallplantationqualityisnothighinChina,andtheproblemslikelowgrowth,lowpreservingrateandlowproductivityarecommonlyobserved.Thispaperreviewedthehistoricalbackgroundoftheresearchonplantationproductivity,describedfactorsaffectingplantationproductivityincludingsiteconditions,initialplantingdensity,thinningmeasures,groundclearance,andcontinuousplantedalgebraandfertilization.Finally,itwasproposedtocarryoutkeytechnologysystemresearchonplantationproductivitymaintenanceandstrengthentheresearchonthelong-termness,systematicdevelopmentandmulti-purposeofplantationproductivity.

简介：研究被进行在C在碱新陈代谢的变化上调查高温的效果。升起我们在福雷斯特植物生态学的关键实验室的幼苗，东北林地大学，Heilongiang，中国。60-day-oldC。玫瑰我们有34片叶子的幼苗与30°C的温度在房间被孵化；为短期的热的40°C震惊实验；20°C，25°C；为长期的实验的35°C。vindoline的内容，catharanthine，vinblastine；在C的长春新碱。玫瑰我们离开；根在短术语(16h)在不同温度被检查；长期(116d)。结果在短期的热吃惊下面显示出那，vindoline的内容，catharanthine；在幼苗的叶子的vinblastine在40°C是更高的与比在30°C，但是在6h处理以后，vindoline的内容；在二温度下面的catharanthine来到了一样的水平。Catharanthine只在C被散布。升起我们根；它的内容被40%在40°C在二小时孵化以后增加，当在30°C孵化慢慢地增加了时；在6h到达了最高的价值。在长期的实验，monomeric碱catharanthine的集中；vindoline比在25°C在20°C是更高的；在35°C的条件下面有锋利的增加。当时为二聚的碱，越高，看了那温度，vinblastine内容的山峰价值越earlier出现。长春新碱有连续改进；达到了0.027mg·g[1]在在比处于另外的条件的那些高的35°C状况下面的第16白天。高温能在C支持不同的碱的累积，这被结束。升起我们；累积特征是高度与处理时间有关。

简介：Background:InWesternNorthAmerica,increasingwildfireandoutbreaksofnativebarkbeetleshavebeenmediatedbywarmingclimateconditions.Bioclimaticmodelsforecastthelossofkeyhighelevationspeciesthroughouttheregion.Thisstudyusesretrospectivevegetationandfirehistorydatatoreconstructthedriversofpastdisturbanceandenvironmentalchange.Understandingtherelationshipamongclimate,antecedentdisturbances,andthelegacyeffectsofsettlement-eraloggingcanhelpidentifythepatternsandprocessesthatcreatelandscapessusceptibletobarkbeetleepidemics.Methods:Ouranalysisusesdatafromlakesedimentcores,standinventories,andhistoricalrecords.Sedimentcoresweredatedwithradiometrictechniques(~(14)Cand~(210)Pb/~(137)Cs)andsubsampledforpollenandcharcoaltomaximizethetemporalresolutionduringthehistoricalperiod(1800CEtopresent)andtoprovideenvironmentalbaselinedata(last10,500years).Pollendataforsprucewerecalibratedtocarbonbiomass(Ct/ha)usingstandardallometricequationsandatransferfunction.Charcoalsampleswereanalyzedwithstatisticalmodelstofacilitatepeakdetectionanddeterminefirerecurrenceintervals.Results:TheWasatchPlateauhasbeendominatedbyEngelmannspruceforestsforthelast~10,500years,withsubalpinefirbecomingmoreprominentsince6000yearsago.Thislandscapehasexperiencedadynamicfireregime,whereburningeventsaremorefrequentandofhighermagnitudeduringthelast3000years.TwoimportantdisturbanceshaveimpactedEngelmannspruceinthehistoricalperiod:1)high-gradeloggingduringthelate19~(th)century;and(2)ahighseveritysprucebeetleoutbreakinthelate20~(th)centurythatkilled>90%ofmaturespruce(>10cmdbh).Conclusions:Ourstudyshowsthatspruce-dominatedforestsinthisregionareresilienttoarangeofclimateanddisturbanceregimes.Severallinesofevidencesuggestthat19~(th)centuryloggingpromotedalegacyofsimplifiedstandstructureandcompositionsuchthat,whencli

简介：Background:Tropicaldryforestscoverlessthan13%oftheworld'stropicalforestsandtheirareaandbiodiversityaredeclining.InsouthernAfrica,themajorthreatisincreasingpopulationpressure,whiledroughtcausedbyclimatechangeisapotentialthreatinthedriertransitionzonestoshrubland.Monitoringclimatechangeimpactsinthesetransitionzonesisdifficultasthereisinadequateinformationonforestcompositiontoallowdisentanglementfromotherenvironmentaldrivers.Methods:Thisstudycombinedhistoricalandmodernforestinventoriescoveringanareaof21,000km~2inatransitionzoneinNamibiaandAngolatodistinguishlatesuccessiontreecommunities,tounderstandtheirdependenceonsitefactors,andtodetecttrendsintheforestcompositionoverthelast40years.Results:Thewoodlandsweredominatedbysixtreespeciesthatrepresented84%ofthetotalbasalareaandcanbereferredtoasBaikiaea-Pterocarpuswoodlands.Aboostedregressiontreeanalysisrevealedthatlatesuccessiontreecommunitiesareprimarilydeterminedbyclimateandtopography.TheSchinziophytonrautaneniiandBaikiaeaplurijugacommunitiesarecommononslightlyinclinedduneorvalleyslopesandhadthehighestbasalarea(5.5-6.2m~2ha~(-1)).TheBurkeaafricana-GuibourtiacoleospermaandPterocarpusangolensis-Dialiumenglerianumcommunitiesaretypicalforthesandyplateauxandhaveahigherproportionofsmallerstemscausedbyahigherfirefrequency.AdecreaseinoverallbasalareaoratrendofincreasingdominationbythemoredroughtandcoldresilientB.africanacommunitywasnotconfirmedbythehistoricaldata,butthereweresignificantdecreasesinbasalareaforOchnapulchraandthevaluablefruittreeD.englerianum.Conclusions:Theslopecommunitiesaremoreshelteredfromfire,frostanddroughtbutaremoresusceptibletohumanexpansion.ThecommunitywiththeimportanttimbertreeP.angolensiscanbestwithstandhighfirefrequencybutshowssignsofahighervulnerabilitytoclimatechange.Conse

简介：Background:Thispaperexploredthelong-term,ceteris-paribuseffectsofpotentialCO,fertilizationontheglobalforestsector.BasedonthefindingsofNorbyetal.(PNAS2005,102(50))aboutforestresponsetoelevated[CO_2].Methods:ForestproductivitywasincreasedintheGlobalForestProductsModel(GFPM)inproportiontotherising[CO.,]projectedintheIPCCscenarioA1B,A2,andB2.Projectionsoftheforestareaandforeststockandoftheproduction,consumption,prices,andtradeofproductsrangingfromfuelwoodtopaperandpaperboardwereobtainedwiththeGFPMforeachscenario,withandwithoutCO_2fertilizationbeginningin2011andupto2065.Results:C02fertilizationincreasedwoodsupply,leadingtolowerwoodpriceswhichinturninducedmodestlowerpricesofendproductsandhigherglobalconsumption.However,productionandvalueaddedinindustriesdecreasedinsomeregionsduetotherelativecompetitiveadvantagesandtothevaryingregionaleffectsofCO_2fertilization.Conclusion:ThemaineffectofCO,fertilizationwastoraisetheleveloftheworldforeststockin2065by9to10%forscenariosA2andB2andby20%forscenarioA1B.Theriseinforeststockinducedbyfertilizationwasinpartcounteractedbyitsstimulationofthewoodsupplywhichresultedinlowerwoodpricesandincreasedharvests.

简介：Background:Stemradialgrowthinforestsisnotuniform.Rather,itischaracterizedbyperiodsofrelativelyfastorslowgrowth,orsometimesnogrowthatall.Thesefluctuationsaregenerallyafunctionofvaryingenvironmentalconditions(e.g.wateravailability)and,importantly,willalsobeassociatedwithadjustmentsinpropertiesinthewoodformed.Standlevelconditionsandforestmanagement,particularlythinningandstanddensitywill,however,alsohaveamajorinfluenceonpatternsofgrowthvariation.Weexplorehowdifferentthinninghistoriesand/orstanddensitiesinfluencethesedynamicsoftreegrowthintheimportantcommercialplantationspeciesPinusradiotaD.Don.Methods:DailystemsizechangewasmeasuredusingelectronicpointdendrometersovertwogrowingseasonsonP.rodiatatreesattwosites,subjectedtodifferentthinningregimes.Timing,ratesandperiodicityofannualgrowthwerecalculatedfromthesedata.Results:Greateroverallcross-seaionalgrowthinthinnedplotswasdrivenmainlybytwodynamics.First,thecessationofseasonalgrowthoccurredatleast3weekslaterinthestandsinwhichthinninghadtakenplace.Therewasnodifferencebetweenthinned/unthinnedstands,however,inthetimingofgrowthonset.Second,withinthelongerseason,treesinthinnedplotshadmoregrowthdays(asmuchas20%more)thanunthinnedplots.Theratesofgrowthondayswhengrowthoccurredwerenotdifferent,however.Inthiscontext,itisnotablethatintreesintheunthinnedplotsexperiencingthemostseverecompetitiontherewerestrongMpulsesMofgrowthfollowingdrought-breakingrainfallevents.Unthinnedplotsathighstanddensitiesalsomaintainedasmaller(butconsistent)zoneofdividingcellsthroughouttheseasonthanthinnedplots.Conclusions:InPinusradiatogrowingunderconditionsasinourstudy,conditionslateinsummer,particularlydrought,haveanimportanteffectonthetimingofcessationofgrowth.Earlyseasontemperatureappearstohavenoeffectin

简介：Background:Themainobjectiveofthisstudywastoexaminetheclimaticsensitivityoftheradialgrowthresponseof13easternwhitepine(PinusstrobusL.)provenancesplantedatseventestsitesthroughoutthenorthernpartofthespecies’nativedistributionineasternNorthAmerica.Methods:Thetestsites(i.e.,Wabeno,Wisconsin,USA;Manistique,Michigan,USA;PineRiver,Michigan,USA;Newaygo,Michigan,USA;TurkeyPoint,Ontario,Canada;Ganaraska,Ontario,Canada;andOrono,Maine,USA)examinedinthisstudywerepartofarange-widewhitepineprovenancetrialestablishedintheearly1960sintheeasternUnitedStatesandCanada.Principalcomponentsanalysis(PCA)wasusedtoexaminethemainmodesofvariation[first(PC1)andsecond(PC2)principalcomponentaxes]inthestandardizedradialgrowthindicesoftheprovenancesateachtestsite.TheyearscoresforPC1andPC2wereexaminedinrelationtoanarrayoftestsiteclimatevariablesusingmultipleregressionanalysistoexaminethecommonalityofgrowthresponseacrossallprovenancestotheclimateofeachtestsite.ProvenanceloadingsonPC1andPC2werecorrelatedwithgeographicparameters(i.e.,latitude,longitude,elevation)andasuiteofbiophysicalparametersassociatedwithprovenanceoriginlocation.Results:TheamountofvariationinradialgrowthexplainedbyPC1andPC2rangedfrom43.4%to89.6%.Dendroclimaticmodelsrevealedthatwhitepineradialgrowthresponsestoclimatewerecomplexanddifferedamongsites.Thekeydendroclimaticrelationshipsobservedincludedsensitivitytohightemperatureinwinterandsummer,coldtemperatureinthespringandfal(i.e.,beginningandendofthegrowingseason),summermoisturestress,potentialsensitivitytostorminduceddamageinspringandfal,andbothpositiveandnegativeeffectsofhigherwintersnowfal.Separationoftheloadingsofprovenancesonprincipalcomponentaxeswasmainlyassociatedwithtemperature-relatedbioclimaticparametersofprovenanceoriginat5ofth